This section introduces aspects that may be helpful in facilitating a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
With the increasing demand for data services, wireless systems tend to use more and more bandwidth and higher carrier frequencies. For example, Fifth Generation (5G) wireless access may be expected to embrace mm-Wave frequencies to provide multi-Gbps data rates, typically in femto, pico, or metro cell type of deployments. Free space propagation or path loss increases at higher frequencies and may be compensated by exploiting antenna directivity. This may be achieved using high gain adaptive BeamForming (BF) solutions. Adaptive beam-steering may be implemented by analog phase shifters, fully digitally, e.g. by equipping each antenna with a fully digital transmit/receive path, or as hybrid digital/analog solutions, e.g. by connecting each digital transmit/receive path to a set of antennas via analog phase shifters. Base station antenna arrays may include, e.g. 8, 16, 32, 64 or more antenna elements, e.g. tiny horn antenna elements.
Document US 2013/0301454 A1 describes a communication method and apparatus using analog and digital hybrid beamforming. Document US 2013/0272263 A1 discloses selecting time, frequency and spatial processing parameters for communications between a base station and a mobile station by transmitting synchronization signals in multiple slices of a wireless transmission sector for the base station.